A CLOSER LOOK: SPORTS INJURIES - Sprains, pains, wrapped up in speculation
Soccer here in the U.S. and Britain suffered a setback in late August: David Beckham sprained his knee and is probably out for the season. The injury comes on the heels of an ankle sprain in the other leg one month earlier. Are the two connected? Here's a look at whether blowing out one joint leads to injury in a second.
The data are scant, says UCLA orthopedic surgeon Dr. David McAllister, because studies looking at the effect of one injury on the risk of hurting some other part of an athlete's body are hard to do. "We would need to identify a lot of people who sequentially got the same two injuries," he says.
Some data exist on whether athletes are more likely to reinjure a previously hurt knee ligament or damage the healthy one instead. One 1998 study of 714 athletes who'd had surgery to repair the anterior cruciate ligament (ACL) of one knee tallied how many tore their previously injured ACL again or hurt their healthy ACL instead. The half who had thinner ligaments were far more likely to damage the ACL in the healthy leg than the half who had thicker ligaments, and most of the thin ACLs belonged to women.
But in a 2007 study of 235 patients, risk of injuring either knee was the same, about 3%, two years after ACL repair.
The best data come from baseball, which is an easier sport than most to study because pitchers tend to injure the same kinds of joints. Players who hurt their elbows are more likely to have shoulder injuries, says orthopedic researcher Brady Tripp of Florida International University in Miami. A 2007 study by Dr. William Grana and colleagues at the University of Arizona Health Sciences Center in Tucson found that of 84 Chicago White Sox pitchers, 27 had elbow ligament injuries, and 60% of the pitchers later had shoulder injuries.
It "is an incredible number. That's two and a half to three times what you'd expect [for shoulder injuries] in an unoperated population," Grana says. "The pitchers try to externally rotate their shoulder to get the velocity they've lost from their elbow surgery." The same study found that of the 60% who had shoulder injuries, half had to have shoulder surgery later on. (Oddly, right-handed pitchers suffered more injuries than left-handed ones. "Right-handed pitchers have to throw harder than left-handed pitchers," Grana says. Lefties can get away with 88 mph on a ball, but righties need to throw above 90 mph for the same effect on batters.)
